Semiconductor light emitting device

ABSTRACT

According to one embodiment, a semiconductor light emitting device includes a stacked structure body, a first electrode, a second electrode, and a dielectric body part. The stacked structure body includes a first semiconductor layer, having a first portion and a second portion juxtaposed with the first portion, a light emitting layer provided on the second portion, a second semiconductor layer provided on the light emitting layer. The first electrode includes a contact part provided on the first portion and contacting the first layer. The second electrode includes a first part provided on the second semiconductor layer and contacting the second layer, and a second part electrically connected with the first part and including a portion overlapping with the contact part when viewed from the first layer toward the second layer. The dielectric body part is provided between the contact part and the second part.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based upon and claims the benefit of priority fromthe prior Japanese Patent Application No. 2011-109921, filed on May 16,2011; the entire contents of which are incorporated herein by reference.

FIELD

Embodiments described herein relate generally to a semiconductor lightemitting device.

BACKGROUND

As a semiconductor light emitting device, such as an LED (Light EmittingDiode), there is a structure in which a crystalline layer formed on, forexample, a sapphire substrate is joined to a conductive substrate, thenthe sapphire substrate is removed. In the structure, in order to enhancelight extraction efficiency, the surface of the crystal layer exposed byremoving the sapphire substrate is subjected to unevenness processing.Moreover, there is also a structure in which no electrode is formed onthe surface of the crystal layer to be a light extraction plane and ap-side electrode and an n-side electrode are formed on a crystal planeopposite to the surface from which the sapphire substrate is removed. Insuch a light emitting device, it is required to further improve thelight extraction efficiency by enhancing the heat dissipation property.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic cross-sectional view illustrating a semiconductorlight emitting device.

FIG. 2 is a schematic plan view illustrating the semiconductor lightemitting device.

FIGS. 3A and 3B are partially enlarged views each illustrating theuneven part.

FIG. 4 is a schematic cross-sectional view illustrating a semiconductorlight emitting device according to a reference example.

FIGS. 5A to 7B are schematic cross-sectional views sequentiallyillustrating a method for manufacturing the semiconductor light emittingdevice.

FIG. 8 is a schematic cross-sectional view illustrating thesemiconductor light emitting device.

FIG. 9 is a schematic plan view illustrating the semiconductor lightemitting device.

FIG. 10 is a schematic plan view illustrating the semiconductor lightemitting device

FIG. 11 is a schematic cross-sectional view illustrating a semiconductorlight emitting apparatus.

DETAILED DESCRIPTION

In general, according to one embodiment, a semiconductor light emittingdevice includes a stacked structure body, a first electrode, a secondelectrode, and a dielectric body part. The stacked structure bodyincludes a first semiconductor layer of a first conductivity type,having a first portion and a second portion juxtaposed with the firstportion in a plane parallel to a layer surface of the firstsemiconductor layer, a light emitting layer provided on the secondportion, a second semiconductor layer of a second conductivity typeprovided on the light emitting layer. The first electrode includes acontact part provided on the first portion and contacting the firstsemiconductor layer. The second electrode includes a first part providedon the second semiconductor layer and contacting the secondsemiconductor layer, and a second part electrically connected with thefirst part and including a portion overlapping with the contact partwhen viewed in a stacking direction from the first semiconductor layertoward the second semiconductor layer. The dielectric body part isprovided between the contact part and the second part.

Various embodiments will be described hereinafter with reference to theaccompanying drawings.

The drawings are schematic or conceptual. The relationship between thethickness and the width of each portion, and the size ratio between theportions, for instance, are not necessarily identical to those inreality. Furthermore, the same portion may be shown with differentdimensions or ratios depending on the figures.

First Embodiment

FIG. 1 is a schematic cross-sectional view illustrating a configurationof a semiconductor light emitting device according to a firstembodiment.

FIG. 2 is a schematic plan view illustrating the configuration of thesemiconductor light emitting device according to the first embodiment.

Here, FIG. 1 illustrates the schematic cross-sectional view at line A-A′in FIG. 2.

As illustrated in FIG. 1, the semiconductor light emitting device 110according to the first embodiment includes a stacked structure body 100,a first electrode 50, a second electrode 60, and a first dielectric bodypart 40.

The stacked structure body 100 includes a first conduction type firstsemiconductor layer 10, a second conduction type second semiconductorlayer 20 facing a part of the first semiconductor layer 10, and a lightemitting layer 30 provided between a part of the first semiconductorlayer 10 and the second semiconductor layer 20.

The first conduction type is, for example, n-type. The second conductiontype is, for example, p-type. The first conduction type may be p-type,and the second conduction type may be n-type. In the embodiment, a casewhere the first conduction type is n-type, and the second conductiontype is p-type, will be exemplified.

The stacked structure body 100 has a first major surface 100 a at theside of the first semiconductor layer 10, and a second major surface 100b at the side of the second semiconductor layer 20. Moreover, a part ofthe first semiconductor layer 10 is exposed to the side of the secondmajor surface 100 b. The part is an exposed part 10 e of the firstsemiconductor layer 10.

The first electrode 50 includes a contact part 51 contacting the firstsemiconductor layer 10 at the exposed part 10 e. The second electrode 60contacts the second semiconductor layer 20 at the second major surface100 b.

The second electrode 60 includes a first part 61 contacting the secondsemiconductor layer 20 at the second major surface 100 b, and a secondpart 62 electrically connected with the first part 61 and including apart overlapping with the contact part 51 viewed from a stackingdirection from the first semiconductor layer 10 toward the secondsemiconductor layer 20.

Here, in the embodiment, Z-axis direction is referred to as a directionconnecting the first semiconductor layer 10 and the second semiconductorlayer 20, X-axis direction is referred to as one direction of twodirections orthogonal to Z-axis direction, and Y-axis direction is adirection orthogonal to Z and X-axis directions. The stacking directionis in Z-axis direction.

Thus, the first semiconductor layer has a first portion (the exposedpart 10 e) and the second portion (other portion 10 f). The secondportion (the other portion 10 f) is juxtaposed with the first portion inX-Y plane (a plane parallel to a layer surface of the firstsemiconductor layer 10).

The first dielectric body part 40 is provided between the contact part51 and the second part 62.

That is, the second electrode 60 is electrically insulated from thefirst electrode 50 through the first dielectric body part 40. In theembodiment, the first dielectric body part 40 is provided only aroundthe contact part 51 of the first electrode 50. Therefore, the first part61 of the second electrode 60 contacts the second semiconductor layer 20at a comparatively large area on which the first dielectric body part 40is not provided at the side of the second major surface 100 b of thestacked structure body 100. Accordingly, the heat generated in thestacked structure body 100 is efficiently dissipated to the exteriorfrom the second electrode 60.

Next, a specific example of the semiconductor light emitting device 110according to the embodiment will be described.

In the semiconductor light emitting device 110 according to theembodiment, the first semiconductor layer 10, the second semiconductorlayer 20, and the luminescence layer 30 included in the stackedstructure body 100 are, for example, nitride semiconductors. The firstsemiconductor layer 10, the second semiconductor layer 20, and the lightemitting layer 30 are stacked on a growth substrate made of sapphireetc. through the use of, for example, a metal organic chemical vapordeposition process.

In the specification, “nitride semiconductor” is set as one ofsemiconductors having all compositions in which x, y and z are changedwithin respective ranges in a chemical formula ofB_(x)In_(y)Al_(z)Ga_(1-x-y-z)N (0≦x≦1, 0≦y≦1, 0≦z≦1, x+y+z≦1).Furthermore, in the above-mentioned chemical formula, one furtherincluding V group elements other than N (nitrogen), one furtherincluding various kinds of elements added to control various kinds ofphysical properties such as conductivity types, and one furtherincluding various kinds of elements contained unintentionally, are alsoincluded in “nitride semiconductor”.

In the stacked structure body 100, a concave part 100 t reaching thefirst semiconductor layer 10 from the second major surface 100 b areprovided. The bottom face of the concave part 100 t includes the exposedpart 10 e of the first semiconductor layer 10. The contact part 51 ofthe first electrode 50 contacts the first semiconductor layer 10 at theexposed part 10 e to achieve electrical connection with the firstsemiconductor layer 10.

A material capable of achieving good contact with the firstsemiconductor layer 10 is used in the contact part 51. As the contactpart 51, for example, a stacking layer of Al/Ni/Au is used. The stackinglayer is formed by stacking Al, Ni and Au on a contact face 50 c in thisorder at a thickness of, for example, 300 nm.

Moreover, the first electrode 50 includes a lead part 53 drawn out tothe exterior of the stacked structure body 100. The lead part 53 iselectrically communicated with the contact part 51 and provided so as toextend to the exterior of the stacked structure body 100 from thecontact part 51 along an X-Y plane. The lead part 53 may be formedintegrally with the contact part 51.

The side face of the stacked structure body 100 is covered with thesecond dielectric body part 45. A part of the lead part 53 is exposedfrom the opening of the second dielectric body part 45 at the exteriorof the stacked structure body 100. A pad electrode 55 is provided on theexposed portion.

A non-illustrated wiring member, such as a bonding wire, is connected tothe pad electrode 55, and thus the exterior and the first semiconductorlayer 10 can be electrically continuous with each other.

The first part 61 of the second electrode 60 is provided so as tocontact the second semiconductor layer 20 along the second major surface100 b. In the first part 61, a material capable of efficientlyreflecting emission light emitted from the light emitting layer 30 isused. In the first part 61, stacking layer of, for example, Ag/Pt isused. The stacking layer is formed by stacking Ag and Pt on the secondmajor surface 100 b in this order at a thickness of, for example, 200nm.

The semiconductor light emitting device 110 according to the embodimentincludes a support substrate 70 is electrically continuous with thesecond part 62 of the second electrode 60. The second part 62 of thesecond electrode 60 includes, for example, a bonding metal part. Thewhole of the second part 62 may be the bonding metal part.

In the bonding metal part, a material capable of achieving a goodconnection with the support substrate 70 to be described below is used.In the bonding metal part, stacking layer of, for example, Ti/Au isused. The stacking layer is formed by stacking Ti and Au on the secondmajor surface 100 b in this order at a thickness of, for example, 800nm.

The support substrate 70 is joined to the bonding metal part. Thesupport substrate 70 is made of a material having at least conductivity.Although, the material of the support substrate 70 is not limited inparticular, for example, a substrate of a semiconductor such as Si andGe, a plate of a metal such as CuW and Cu, and a thick film plated layerare used. Moreover, the substrate is not required to have a conductivityon the whole, and the substrate may be a resin substrate with a metalinterconnect or the like.

In the embodiment, as an example of the material of the supportsubstrate 70, Ge is used. The support substrate 70 is joined to thebonding metal part through a solder of, for example, Au/Su alloy (notillustrated).

A back face electrode 85 is provided to the support substrate 70. Thatis, the second semiconductor layer 20 is electrically continuous withthe second electrode 60, the support substrate 70, and the back faceelectrode 85. Thus, mounting the semiconductor light emitting device 110on a non-illustrated mounting substrate etc., enables to achieveelectric communication between an electric communication part providedto the mounting substrate etc. and the second semiconductor layer 20.

The support substrate 70, viewed in X-axis direction, has an edge part70 a of the exterior of the stacked structure body 100. The lead part 53of the first electrode 50 is drawn out from the contact part 51 to theedge part 70 a.

In the semiconductor light emitting device 110, the second electrode 60is a p-side electrode. Accordingly, the support substrate 70 and theback face electrode 85 electrically continuous with the second electrode60 can achieve electric communication between the p-side electrode (thesecond electrode 60) and the exterior.

Moreover, in the semiconductor light emitting device 110, the firstelectrode 50 is an n-side electrode. Accordingly, connecting a wiringmember such as a bonding wire to the pad electrode 55 allows obtainingelectric communication between the n-side electrode (the first electrode50) and the exterior.

In the semiconductor light emitting device 110, an uneven part 12 p maybe provided on the first major surface 100 a (surface of the firstsemiconductor layer 10) of the stacked structure body 100. The unevenpart 12 p is constituted by a plurality of projections provided on aplane of the first major surface 100 a.

FIGS. 3A and 3B are partially enlarged views each illustrating theuneven part.

FIG. 3A is a schematic cross-sectional view of the uneven part.

FIG. 3B is a schematic plan view of one convex part.

As illustrated in FIG. 3A, the uneven part 12 p is provided with aplurality of protrusions. The maximum width of the protrusions alongX-axis direction is longer than a peak wavelength in the firstsemiconductor layer 10 of emission light radiated from the lightemitting layer 30.

Thus, reflection of emission light at the interface of the firstsemiconductor layer 10 and the outside can be considered as Lambertreflection, thereby resulting in a higher improvement effect of lightextraction efficiency. Where, “peak wavelength” is referred to as awavelength of highest intensity light among emission light radiated fromthe light emitting layer 30. The peak wavelength is a wavelengthcorresponding to a peak value of spectrum distribution of the emissionlight. When a spectrum has two or more maximum values, each of which isnot a noise level, a wavelength of either of them may be selected.

As illustrated in FIG. 3B, for example, when a nitride semiconductor isused in the first semiconductor layer 10, if a planar shape of theprotrusions viewed in Z-axis direction is an approximate hexagon, themaximum width ΔW is the width between opposite diagonal vertices of thehexagon.

As an example, when the first semiconductor layer 10 is made of galliumnitride, and the peak wavelength of emission light of the light emittinglayer 30 is 390 nm, the peak wavelength of emission light in theluminescence layer 10 becomes 155 nm. In this case, the improvementeffect of light extraction efficiency can be achieved until the maximumwidth ΔW of the uneven part 12 p reaches an order of 3 μm from a valueexceeding 155 nm. Thus, it is preferable that the maximum width ΔW ofthe uneven part 12 p is not less than twice the peak wavelength of theemission light, and it is more preferable that the maximum width ΔW isnot less than ten times the peak wavelength.

In such semiconductor light emitting device 110, the quantity of lightemitted from the light emitting layer 30 is larger at the side of thefirst major surface 100 a than at the side of the second major surface100 b of the stacked structure body 100. That is, the first majorsurface 100 a acts as a light extraction plane.

In the semiconductor light emitting device 110, neither the n-sideelectrode (the first electrode 50) nor the p-side electrode (the secondelectrode 60) is arranged at the first major surface 100 a side of thestacked structure body 100. Accordingly, in this case, the lightextraction efficiency at the first major surface 100 a side is improvedthan a case where the electrodes are arranged on the side of the firstmajor surface 100 a. Furthermore, the p-side electrode (the secondelectrode 60) located directly below the light emitting layer 30, whichis a main source of heat generation, is connected to a metal layer andthe support substrate 70 with high thermal conductivity. If, forexample, a heat sink is connected to the support substrate 70, heatresistance can be made low and good heat dissipation property can beachieved. In addition to this, the second part 62 of the p-sideelectrode (the second electrode 60) of the semiconductor light emittingdevice 110 is provided so as to extend along the second major surface100 b of the stacked structure body 100. For example, the supportsubstrate 70 has the edge part 70 a, which is located outer the stackedstructure body 100 a as viewed in the stacking direction. The secondpart 62 extends along the second major surface 100 b to the edge part 70a. Thus, good heat diffusion can be achieved, enabling heat resistanceof the whole of the semiconductor light emitting device 110 to be lower.

FIG. 4 is a schematic cross-sectional view illustrating a configurationof a semiconductor light emitting device according to a referenceexample.

As illustrated in FIG. 4, in the semiconductor light emitting device 190according to the reference example, a first electrode 50 includes acontact part 51 and a third part 54, which is electrically continuouswith the contact part 51 and provided along a second major surface 100b. Furthermore, a third dielectric body part 41 is provided between thethird part and a first part 61 of a second electrode 60 along Z-axisdirection.

The second electrode 60 includes a first part 61 and a lead part 63,which electrically continuous with the first part 61 and is providedfrom the first part 61 the outside of a stacked structure body 100. Apart of the lead part 63 is exposed from an opening of a seconddielectric body part 45 at the exterior of the stacked structure body100. A pad electrode 65 is provided on the exposed portion.

In such a semiconductor light emitting device 190, the third dielectricbody part 41 is provided between the first part 61 of the secondelectrode 60 and the third part 54 of the first electrode 50. That is,the third dielectric body part 41 is formed to cover the whole of thefirst electrode 50 except the contact part 51 at the side of the secondmajor surface 100 b of the stacked structure body 100. Accordingly, apart located directly below the light emitting layer 30, which is a mainsource of heat generation, is covered with the third dielectric bodypart 41. Since the semiconductor light emitting device 190 is connectedto a heat sink etc. through the third dielectric body part 41 with heatconductivity lower than that of a metal, heat resistance of the device190 becomes high, thereby not being able to obtain sufficient heatdissipation property of the device 190. Furthermore, since, in order toimprove the insulation property, it is necessary for the thirddielectric body part 41 to be formed to be thick, the insulationproperty and the heat dissipation property of the device 190 are in atrade-off relation to each other.

In contrast, in the semiconductor light emitting device 110 according tothe embodiment, a dielectric body is not provided directly below thelight emitting layer 30. The second electrode 60 is located directlybelow the luminescence layer 30, and thus heat generated in theluminescence layer 30 spreads from the second electrode 60 to a side ofthe support substrate 70 and is easily dissipated outside. Accordingly,even if the first dielectric body part 40 is formed so as to be thickfor the purpose of improving the insulation property, the heatdissipation property is not be reduced. Therefore, in the semiconductorlight emitting device 110, the good insulation property and the goodheat dissipation property can be achieved simultaneously.

Next, an example of a method for manufacturing the semiconductor lightemitting device 110 will be described.

FIGS. 5A to 7B are schematic cross-sectional views sequentiallyillustrating an example of the method for manufacturing thesemiconductor light emitting device.

First, as illustrated in FIG. 5A, the first semiconductor layer 10, thelight emitting layer 30, and the second semiconductor layer 20 aresequentially grown on the growth substrate 80 made of sapphire etc.Thus, the stacked structure body 100 is formed on the growth substrate80.

The stacked structure body 100 is formed using, for example, a metalorganic chemical vapor deposition process. As a method for forming thestacked structure body 100, a well-known technology such as a molecularbeam epitaxy growth process, may be used other than the metal organicchemical vapor deposition process.

As an example, the stacked structure body 100 is formed as follows.

First, as a buffer layer, a high carbon-concentration first AlN bufferlayer (the carbon concentration is, for example, not less than 3×10¹⁸cm⁻³ and not more than 5×10²⁰ cm⁻³, and the thickness is, for example, 3nm to 20 nm), a high purity second AlN buffer layer (the carbonconcentration is, for example, not less than 1×10¹⁶ cm⁻³ and not morethan 3×10¹⁸ cm⁻³, and the thickness is 2 μm), and a non-doped GaN bufferlayer (the thickness is, for example, 2 μm) are formed in this order ona growth substrate 80, the surface of which is made up of sapphirec-plane. The first AlN buffer layer and the second AlN buffer layermentioned above are layers made up of single crystal aluminum nitride.By using single crystal aluminum nitride layers as the first AlN bufferlayer and the second AlN buffer layer, a high quality semiconductorlayer can be formed in crystal growth described later, resulting insignificant reduction of damage to a crystal.

Next, a Si doped n-type GaN contact layer (the Si concentration is, forexample, not less than 1×10¹⁸ cm⁻³ and not more than 5×10¹⁹ cm⁻³, andthe thickness is 6 μm), and a Si doped n-type Al_(0.10)Ga_(0.90)Ncladding layer (for example, the Si concentration is 1×10¹⁸ cm⁻³ and thethickness is 0.02 μm) are formed thereon in this order. The Si dopedn-type GaN contact layer and the Si doped n-type Al_(0.10)Ga_(0.90)Ncladding layer constitute the first semiconductor layer 10. Forconvenience, all or a part of the above-mentioned GaN buffer layers maybe included in the first semiconductor layers 10.

Here, the buffer layer formed on the growth substrate 80 is not limitedto AlN mentioned above. For example, a thin film made up ofAl_(x)Ga_(1-x)N (0≦x≦1) grown at a low-temperature may be used.

Next, as a luminescence layer 30, a Si doped n-type Al_(0.11)Ga_(0.89)Nbarrier layer, a GaInN well layer, are alternately stacked thereon forthree periods, and then a final Al_(0.11)Ga_(0.89)N barrier layer withmulti quantum wells is further stacked thereon. In the Si doped n-typeAl_(0.11)Ga_(0.89)N barrier layer, the Si concentration is, for example,not less than 1.1×10¹⁹ cm⁻³ and not more than 1.5×10¹⁹ cm⁻³. In thefinal Al_(0.11)Ga_(0.89)N barrier layer, the Si concentration is, forexample, not less than 1.1×10¹⁹ cm⁻³ and not more than 1.5×10¹⁹ cm⁻³,and the thickness is, for example, 0.01 μm. The thickness of such amulti quantum wells structure is, for example, 0.075 μm. Subsequently, aSi doped n-type Al_(0.11)Ga_(0.89)N layer (the Si concentration is, forexample, not less than 0.8×10¹⁹ cm⁻³ and not more than 1.0×10¹⁹ cm⁻³,and the thickness is, for example, 0.01 μm) is formed thereon. Thewavelength of the emission light in the light emitting layer 30 is, forexample, not less than 370 nm and not more than 480 nm, or not less than370 nm and not more than 400 nm.

Furthermore, as a second semiconductor layer 20, a non-dopedAl_(0.11)Ga_(0.89)N spacer layer (the thickness is, for example, 0.02μm), a Mg doped p-type Al_(0.28)Ga_(0.72)N cladding layer (the Mgconcentration is, for example, 1×10¹⁹ cm⁻³, and the thickness is, forexample, 0.02 μm), and a Mg doped p-type GaN contact layer (the Mgconcentration is, for example, 1×10¹⁹ cm⁻³, and the thickness is, forexample, 0.4 μm), and a high concentration Mg doped p-type GaN contactlayer (the Mg concentration is, for example, 5×10¹⁹ cm⁻³, and thethickness is, for example, 0.02 μm) are formed thereon one by one inthis order.

The above-mentioned compositions, compositional ratios, kind ofimpurities, impurity concentrations, and thicknesses are one ofexamples, and various modifications with regard to the example arepossible.

By setting the Mg concentration of the high concentration Mg dopedp-type GaN contact layer to a higher value of 1×10²⁰ cm⁻³, the ohmiccharacteristics with respect to the second electrode 60 can be improved.However, in the case of a semiconductor light emitting diode, unlike asemiconductor laser diode, the distance between the high-concentrationMg doped p-type GaN contact layer and the light emitting layer 30 isnear, and thus the degradation of characteristics due to Mg diffusion isa concern. Therefore, by suppressing the Mg concentration of the highconcentration Mg doped p-type GaN contact layer to be approximately1×10¹⁹ cm⁻³ without significant degradation of the electric properties,Mg diffusion can be suppressed, thereby resulting in improvement of thelight emission characteristics.

Moreover, the high carbon concentration first AlN buffer layer has afunction to relax difference in crystal type with respect to the growthsubstrate 80, and especially it reduces screw dislocation. Moreover, thesurface of the high purity second AlN buffer layer is made flat at theatomic level. Therefore, crystal defects of the non-doped GaN bufferlayer grown thereon are reduced. In order to sufficiently reduce thecrystal defects, it is preferable to make film thickness of the secondAlN buffer layer thicker than 1 μm. Moreover, in order to suppresswarpage due to distortion, it is preferable to make the film thicknessof the second AlN buffer layer to be not more than 4 μm. The material ofthe high purity second AlN buffer layer is not limited to AlN, instead,Al_(x)Ga_(1-x)N (0.8≦x≦1) may be used as the material and it cancompensate the warpage of the growth substrate 80.

Moreover, the non-doped GaN buffer layer is grown in the shape of athree-dimensional island on the high purity second AlN buffer layer.Thus, the non-doped GaN buffer layer plays a role in reducing crystaldefects. In order to make the growth surface flat, it is preferable thatthe average film thickness of the non-doped GaN buffer layer is not lessthan 2 μm. In view of reproducibility and warpage reduction, it ispreferable that the total film thickness of the non-doped GaN bufferlayer is not less than 2 μm and not more than 10 μm.

By adopting such a buffer layer, the crystal defects can be reduced toapproximately 1/10 compared with those of a case where the AlN bufferlayer grown at a low temperature is adopted. Although this technologymakes use of high concentration Si doping to the n-type GaN contactlayer and light emission at a frequency band of ultraviolet light, ahigh efficiency semiconductor light emitting device is manufacturedthrough the use of the technology. Furthermore, by reducing the crystaldefects in the non-doped GaN buffer layer, light absorption in thenon-doped GaN buffer layer is also suppressed.

Although the light emission wavelength of the quantum well layer is notlimited in particular, when using for example, a gallium nitride basedcompound semiconductor made up of GaInN, 375 to 700 nm luminescence isachieved.

Moreover, the buffer layer on the sapphire substrate is not limited inparticular, and a Al_(x)Ga_(1-x)N (0≦x≦1) thin film grown at alow-temperature may be used.

Next, as illustrated in FIG. 5B, the concave part 100 t is formed in apart of the stacked structure body 100. The concave part 100 t reachesthe first semiconductor layer 10 from the second major surface 100 b ofthe stacked structure body 100. Thus, the first semiconductor layer 10is exposed to the bottom of the concave part 100 t (exposed part 10 e).

In order to form the concave part 100 t, a non-illustrated mask isformed on the second major surface 100 b of the stacked structure body100, and is subjected to, for example, dry etching. That is, an openingis provided in the mask at a portion to be formed with the concave part100 t, and the stacked structure body 100 is removed from the secondmajor surface 100 b to the first semiconductor layer 10 by means ofetching. Thus, the concave part 100 t is formed. Although the angle ofthe internal face of the concave part 100 t is not limited inparticular, it is preferable that the angle is not less than 60° as anangle for reflecting emission light from the light emitting layer 30,having maximum intensity at 30°, in a direction opposite to theadvancing direction. Although the depth of the concave part 100 t is notlimited in particular, as the depth becomes deeper the light extractionefficiency is improved more easily by changing the advancing directionof emission light propagating inside the stacked structure body 100 in atransverse direction. In contrast, if the depth is too deep, it becomesdifficult to fill the concave part 100 t with solder, in bonding thesupport substrate 70 at a later process. Furthermore, if the depth ofthe concave part 100 t is made deep until it reaches to the non-dopedGaN buffer layer, it becomes impossible to form the first electrode 50in the Si doped n-type GaN contact layer. Accordingly, the depth of theconcave part 100 t is made to be, for example, not less than 0.6 μm andnot more than 6.6 μm, preferably, not less than 1.0 μm and not more than3.0 μm.

Next, as illustrated in FIG. 5B, the first electrode 50 contacting thefirst semiconductor layer 10 is formed. For the first electrode 50,first, a stacking layer of Ti/Al/Ni/Au to be an ohmic electrode isformed on an exposed face 100 e of the first semiconductor layer 10exposed from the concave part 100 t, at a film thickness of, forexample, 300 nm, and the stacking layer is sintered at 600° C. for 5minutes in a nitrogen atmosphere.

Next, as a metal for current diffusion, a joint metal for the lead part53 to the pad electrode 55, and an adhesion metal to an insulatinglayer, a stacking layer of, for example, Ti/Au/Ti is formed on an ohmicelectrode at a film thickness of, for example, 1200 nm.

The material for the first electrode 50 is not limited to one mentionedabove. For example, if Al is used as a material for a first layer, thelight extraction efficiency and the design degree of freedom of thefirst electrode 50 is improved, because, the first layer acts as areflection electrode while achieving good ohmic characteristics and lowcontact characteristics with respect to the n-type contact layer. SinceAl has a poor environmental resistance, for example, by adopting an Alalloy mixed with slight Si, the reliability and the adhesion property ofthe electrode can be improved.

Next, the first dielectric body part 40 is formed so as to cover thefirst electrode 50 and the concave part 100 t. As the first dielectricbody part 40, for example, a film of SiO₂ is formed at the filmthickness of 800 nm.

Here, when forming a film of the first dielectric body part 40, filmformation by high temperature growth can be applied. That is, since thefirst electrode 50 formed previously is sintered at about 600° C., ithas heat-resistance to comparable heat treatment conditions.Accordingly, film formation of the first dielectric body part 40 may beformed at a sufficiently high temperature. Therefore, the firstdielectric body part 40 becomes a high quality film excellent in theinsulation property, the coverage, the reliability and so on.

Next, as illustrated in FIG. 5C, in order to form the second electrode60 with ohmic characteristics, the first dielectric body part 40 on thesecond semiconductor layer 20 is removed. Then, a stacking layer ofAg/Pt to be an ohmic electrode is formed on the surface of the secondsemiconductor layer 20 exposed by removing the first dielectric bodypart 40 at a thickness of, for example, 200 nm. Then, a first part 61 ofthe second electrode 60 is formed by sintering the stacking layer atabout 400° C. for one minute in an oxygen atmosphere.

The second electrode 60 at least contains silver or silver alloy.Although reflection efficiency of an usual metal single layer film inthe visible light frequency band tends to decrease as the wavelengthbecomes shorter in the ultraviolet frequency band not more than 400 nm,silver has high reflection efficiency characteristics high even forlight in the ultraviolet frequency band not less than 370 nm and notmore than 400 nm. Therefore, when the second electrode 60 is made of asilver alloy in a semiconductor light emitting device of ultravioletemission, it is desirable for the second electrode 60 on thesemiconductor interface side to have a larger silver component ratio. Inorder to ensure the reflection efficiency for light, it is preferablethat the film thickness of the second electrode 60 is not less than 100nm.

Next, as illustrated in FIG. 6A, on the whole of the surfaces on whichthe first part 61 and the first dielectric body part 40 are exposed, astacking layer of, for example, Ti/Pt/Au is formed as a second part 62to be a joint metal, at a film thickness of, for example, 800 nm.

Next, the support substrate 70 made of, for example, Ge is prepared. Onthe major surface of the support substrate 70, for example, a solder(not illustrated) composed of an AuSn alloy is provided at a filmthickness of 3 μm. Then, while facing the second part 62 and the solderto each other, the substrate 70 and the stacked structure 100 are heatedto a temperature of, for example, 300° C., exceeding the eutectic pointof the solder. Thus, the support substrate 70 is joined to the side ofthe second major surface 100 b of the stacked structure body 100.

Then, as illustrated in FIG. 6B, the stacked structure body 100 isirradiated with laser light LSR of the third harmonic (355 nm) or thefourth harmonic (266 nm) of a solid-state laser of, for example, YVO₄from the side of the growth substrate 80. The wavelength of the laserlight LSR is shorter than the band-gap wavelength based on the band gapof GaN in a GaN buffer layer (for example, the above-mentioned non-dopedGaN buffer layer). That is, the laser light LSR has energy higher thanthe band gap of GaN.

This laser light LSR is efficiently absorbed in an area at the side of asingle crystal AlN buffer layer (in this example, the second AlN bufferlayer) in the GaN buffer layer (non-doped GaN buffer layer). Thus, GaNat the side of the single crystal AlN buffer layer in the GaN bufferlayer is decomposed by heat generation.

When adhering the crystal layer on the sapphire substrate (the growthsubstrate 80) and the support substrate 70 together, or when releasingthe sapphire substrate (the growth substrate 80) from the supportsubstrate 70 by decomposing GaN through the use of the laser light LSR,crystal defects and damages tend to occur in the crystals due todifference in the thermal expansion coefficient between the supportsubstrate 70 and sapphire or GaN, heat generated by local heating,products generated when GaN decomposes, and the like. If the crystaldefects and damages are generated, Ag of the second electrode 60diffuses, thereby accelerating increase of leakages in the crystals andcrystal defects.

According to the embodiment, since a high quality semiconductor layercan be formed through the use of a single crystal AlN buffer layer, thedamages to crystals are significantly reduced. Furthermore, whendecomposing GaN with the laser light LSR, heat is diffused into the AlNbuffer layer located in the immediate vicinity of GaN and exhibitinghigh thermal conduction characteristics, and thus the crystals arehardly damaged by the heat due to local heating.

Then, the decomposed GaN is removed by a hydrochloric acid treatmentetc. to release the growth substrate 80 from the stacked structure body100. Thus, the growth substrate 80 and the stacked structure body 100are separated.

Next, the formation of unevenness and the pad electrode 55 is carriedout on the exposed first major surface 100 a of the stacked structurebody 100.

First, as illustrated in FIG. 7A, a part of the stacked structure body100 is removed by dry etching to expose a part of the first electrode 50(the lead part 53). Next, the second dielectric body part 45 is formedon the entire face of the first major surface 100 a of the stackedstructure body 100, and an opening is provided in a portion thereof. Inthe second dielectric body part 45, for example, SiO₂ is used. The filmthickness of the second dielectric body part 45 is, for example, 800 nm.From the opening of the second dielectric body part 45, the surface of,for example, a non-doped GaN buffer layer is exposed.

Next, as illustrated in FIG. 7B, through the use of the seconddielectric body part 45 provided with the opening as a mask, the surfaceof the non-doped GaN buffer layer is processed by alkali etching using,for example, a KOH solution to form the uneven part 12 p. As etchingconditions, for example, the KOH solution of 1 mol/liter is heated to80° C., and etching is carried out for 20 minutes.

The uneven part 12 p may be formed on the n-type contact layer. However,in order to form low resistance ohmic contact with the n-side electrode(first electrode 50), career concentration (for example, impurityconcentration) of the n-type contact layer is set to be high. Whenforming unevenness and a flat part on the n-type contact layer, surfaceroughening and impurity precipitation may occur, resulting in factors ofreducing light extraction efficiency. In contrast, the impurityconcentration of the GaN buffer layer is lower than that of the n-typecontact layer, which is therefore advantageous in that surfaceroughening and impurity precipitation hardly occur.

Here, in the method of forming uneven part 12 p, wet etching asmentioned above may be used, or dry etching may be used. For alkalietching using a KOH solution etc., anisotropic etching is carried outwith respect to the buffer layer along the plane direction (mainly {1 0−1 −1}) of each GaN crystal, resulting in formation of a structure ofsix-sided pyramids. Moreover, the etching rate, and the dimension anddensity of the six-sided pyramids are changed largely depending on thehydrogen ion exponent (pH) (adjustable by an etching temperature, anetching time, and addition of another substance), concentration,presence of radiation of ultraviolet (UV) light and UV laser, and thelike.

In general, as the amount of etching (depth from the surface beforeetching to the deepest place of the uneven part 12 p made after etching)becomes larger, the uneven part 12 p formed becomes larger and denser.When processing GaN by dry etching, unlike a Ga plane, an N plane tendsto be influenced by crystal orientation or dislocation, and can beeasily subjected to anisotropic etching. The surface of GaN grown on thec-plane sapphire substrate is usually the Ga plane, and the surface ofGaN exposed by removing the sapphire substrate like the embodiment isthe N plane. Accordingly, it is easy to form the uneven part 12 p byanisotropic etching using dry etching. The uneven part 12 p may also beformed by anisotropic etching using a mask. Thus, the uneven part 12 pas designed can be formed, thereby allowing the improvement of lightextraction efficiency.

The uneven part 12 p is provided for purposes of, for example,extracting incident emission light effectively or changing an incidentangle. Therefore, it is preferable that the dimension of the uneven part12 p is larger than that of the wavelength of the emission light in thecrystal layer. If the dimension of the uneven part 12 p is smaller thanthat of the wavelength of the emission light, at the interface of theuneven part 12 p, the incident emission light in the uneven part 12 pexhibits phenomena, such as scattering and diffraction, which can beexplained by wave optics. Thus, a part of emission light originallybeing penetrated therethrough is not extracted. Furthermore, if thedimension of the uneven part 12 p is sufficiently smaller than that ofthe wavelength of the emission light, the uneven part 12 p is consideredas a layer in which its refractive index is continuously changed.Therefore, the layer acts like a flat plane without unevenness, notallowing the improvement of the light extraction efficiency.

According to experimental results using a semiconductor light emittingdevice (the wavelength of emission light in a crystal layer is about 155nm) having a wavelength of emission light of 390 nm, produced in theembodiment, a tendency that as the dimension of the uneven part 12 pbecame larger the optical output increased, was demonstrated. Thetendency of increase of the output moderately continued until thedimension of the uneven part 12 p became to an order of 3 μm. Thus, itwas found it is preferable that the dimension of the uneven part 12 p isnot less than twice that of the emission light in the crystal layer, andfurther preferable that the dimension of the uneven part 12 p is to benot less than ten times.

Next, a part of the second dielectric body part 45 covering the leadpart 53 is removed, and the pad electrode 55 is formed on a part of theexposed lead part 53. As a pad electrode 55, a stacking layer of, forexample, Ti/Pt/Au is used. The film thickness of the pad electrode 55 is800 nm, for example. A bonding wire is connected to the pad electrode55.

Then, the support substrate 70 is ground to a thickness of about 100 μmby grinding etc. and a stacking layer of, for example, Ti/Pt/Au isformed on the ground surface at a thickness of, for example, 800 nm as aback face electrode 85. The back face electrode 85 is connected to aheat sink or a package.

Subsequently, if necessary, the support substrate 70 is cut out by usingcleavage or a diamond blade etc. Thus, the semiconductor light emittingdevice 110 is completed.

Although in the above-mentioned manufacturing method, an example inwhich the sapphire substrate is used as the growth substrate 80 isshown, a Si substrate may be used as the growth substrate 80.Furthermore, when the Si substrate is used as the growth substrate 80,instead of using radiation of laser light LSR, a treatment for removingthe growth substrate 80 may be carried out by grinding the Si substrateto a certain degree of thickness and subsequently removing the remainingSi substrate by etching.

Second Embodiment

FIG. 8 is a schematic cross-sectional view illustrating a configurationof a semiconductor light emitting device according to a secondembodiment.

FIG. 9 is a surface-side schematic plan view illustrating theconfiguration of the semiconductor light emitting device according tothe second embodiment.

FIG. 10 is a back-face-side schematic plan view illustrating theconfiguration of the semiconductor light emitting device according tothe second embodiment.

Here, FIG. 8 illustrates the schematic cross-sectional view at line B-B′in FIG. 9.

As illustrated in FIG. 8, the semiconductor light emitting device 120according to the second embodiment includes a stacked structure body100, a first electrode 50, a second electrode 60, and a first dielectricbody part 40. The semiconductor light emitting device 120 also includesa pad electrode 57 electrically continuous with the first electrode. Thepad electrode 57 is arranged in parallel with a second part 62 of thesecond electrode.

A via part 56 is provided between the pad electrode 57 and a contactpart 51 of the first electrode 50. The via part 56 extends along Z-axisdirection. For example, the via part 56 is formed inside a hole Hpenetrating through the second part 62 of the second electrode 60 inZ-axis direction. The via part 56 is formed inside the hole H through anembedding insulator part 43. For the embedding insulator part 43, forexample, a dielectric material (SiO₂ etc.) is used. For the embeddinginsulator part 43, a resin may also be used. The via part 56electrically connect the pad electrode 57 to the contact part 51. Thevia part 56 may be included in the first electrode 50.

In the semiconductor light emitting device 120, the second part 62 ofthe second electrode 60 is formed, for example, with a plated metal.That is, the second part 62 is formed by metal plating. As the platedmetal, for example, Cu is used. By metal plating, the second part 62 isformed at a thickness of about 200 μm. Thus, the second part 62 is givensufficient strength, and can be used as the support substrate 70 (referto FIG. 1).

The second electrode 60 may be formed by plating the first part 61 andthe second part 62.

As mentioned above, in the semiconductor light emitting device 120, thepad electrode 57 is arranged in parallel with the second part 62 of thesecond electrode 60. That is, in the semiconductor light emitting device120, both the first electrode 50 and the second electrode 60 arearranged at the opposite side (the side of a second major surface 100 b)with a light extraction plane (a first major surface 100 a) of thestacked structure body 100. The first electrode 50 and the secondelectrode 60 are not arranged on the light extraction plane (refer toFIGS. 8 and 9). Accordingly, the area of the light extraction plane canbe enlarged than that of a light emitting device in which an electrodeis arranged at the side of the light extraction plane. Thus, effectivecurrent density is decreased, resulting in improvement of luminousefficiency.

Moreover, since the pad electrode 57 is electrically continuous with thecontact part 51 through the via part 56, it is possible to lay out thepad electrode 57 freely at the back face side (the side of the secondmajor surface 100 b) of the semiconductor light emitting device 120. Asillustrated in FIG. 10, the pad electrode 57 may be provided on aplurality of places on a plane at the back face side. The pad electrode57 may also be formed on corners (at least one corner) at the back faceside. Furthermore, the pad electrode 57 may also be formed on thecentral part at the back face side. In the semiconductor light emittingdevice 120, the layout of the pad electrode 57 can be easily set inconsideration of how current flows between the first electrode 50 andthe second electrode 60.

FIG. 11 is a schematic cross-sectional view illustrating a configurationof a semiconductor light emitting apparatus using a semiconductor lightemitting device according to an embodiment.

In this specific example, although the semiconductor light emittingdevice 110 according to the first embodiment is used, it is alsopossible for the semiconductor light emitting apparatus to use thesemiconductor light emitting device 120 according to the otherembodiment.

The semiconductor light emitting apparatus 500 is a white LED in whichthe semiconductor light emitting device 110 and a fluorescent materialare combined. That is, the semiconductor light emitting apparatus 500according to the embodiment includes the semiconductor light emittingdevice 110, and the fluorescent material which absorbs light emittedfrom the semiconductor light emitting device 110 and emits light ofwhich wavelength is different from that of the above light.

As illustrated in FIG. 11, in the semiconductor light emitting apparatus500 according to the embodiment, a reflective film 73 is provided on theinner face of a container 72 made of ceramics etc. The reflective film73 is separately formed on the inner sidewall and the bottom of thecontainer 72. The reflective film 73 is made of, for example, aluminum.Among them, on the reflective film 73 provided on the bottom of thecontainer 72, the semiconductor light emitting device 110 is installedthrough a submount 74.

For the semiconductor light emitting device 110, while directing theside of the first major surface 100 a upwards, the back face of itssupport substrate 70 is fixed to the submount 74. It is also possible tomake use of adhesion through the use of adhesives, for fixation of thesemiconductor light emitting device 110, the submount 74, and thereflective film 73.

An electrode 75 is provided on the surface of the submount 74 at theside of the semiconductor light emitting device 110. The supportsubstrate 70 of the semiconductor light emitting device 110 is mountedon the electrode 75 through the back face electrode 85. Therefore, theelectrode is electrically continuous with the second electrode 60through the back face electrode 85 and the support substrate 70. The padelectrode 55 is connected to a non-illustrated electrode provided at theside of the container 72 using a bonding wire 76. These connection worksare carried out between the inner sidewall side reflective film 73 andthe bottom face side reflective film 73.

Moreover, a first fluorescent material layer 81 containing a redfluorescent material is provided so as to cover the semiconductor lightemitting device 110 and the bonding wire 76. Furthermore, on the firstfluorescent material layer 81, a second fluorescent material layer 82containing a fluorescent material of blue, green, or yellow is formed.On the fluorescent material layer, a lid part 77 made of, such as asilicone resin, is provided.

The first fluorescent material layer 81 includes a resin and the redfluorescent material dispersed in the resin.

For the red fluorescent material, for example, Y₂O₃, YVO₄, or Y₂(P, V)O₄may be used as a base material, and trivalent Eu (Eu³⁺) is included inthe matrix as an activation material. That is, Y₂O₃:Eu³⁺, YVO₄:Eu³⁺ orthe like may be used as the red fluorescent material. The concentrationof Eu³⁺ can be 1% to 10% in terms of molarity.

For the base material of the red fluorescent material, LaOS, Y₂(P, V)O₄,or the like may also be used instead of Y₂O₃ or YVO₄. Furthermore, Mn⁴⁺or the like may also be used instead of Eu³⁺. In particular, by addingtrivalent Eu and a small amount of Bi to the base material of YVO₄, theabsorption at 390 nm increases, and thus the luminous efficiency can befurther enhanced. Moreover, for the resin, for example, silicone resinmay be used.

Moreover, the second fluorescent material layer 82 includes a resin andat least any one of blue, green, and yellow fluorescent materialsdispersed in the resin. For example, as the fluorescent material, afluorescent material combining the blue fluorescent material and thegreen fluorescent material may be used, or a fluorescent materialcombining the blue fluorescent material and the yellow fluorescentmaterial may be used, or a fluorescent material combining the bluefluorescent material, the green fluorescent material, and the yellowfluorescent material may be used.

As the blue fluorescent material, for example, (Sr, Ca)₁₀(PO₄)₆C₁₂:Eu²⁺or BaMg₂Al₁₆O₂₇:Eu²⁺ may be used.

As the green fluorescent material, for example, Y₂SiO₅:Ce³⁺,Tb³⁺ usingtrivalent Tb as the emission center may be used. In this case, theexcitation efficiency is improved because the energy is transferred fromthe Ce ion to the Tb ion. As the green fluorescent material, forexample, Sr₄Al₁₄O₂₅:Eu²⁺ may also be used.

As the yellow fluorescent material, for example, Y₃Al₅:Ce³⁺ may be used.

Moreover, as the resin, for example, a silicone resin may be used. Inparticular, trivalent Tb exhibits sharp emission in the vicinity of 550nm where the luminous efficiency is maximized, and thus, when trivalentTb is combined with the sharp red emission of trivalent Eu, the luminousefficiency is significantly improved.

According to the semiconductor light emitting apparatus 500 according tothe embodiment, the ultraviolet light generated by the semiconductorlight emitting device 110 and having wavelength of, for example, 390 nmis emitted upwards and laterally from the device 110. Furthermore, theabove fluorescent materials included in each of the fluorescent materiallayers are efficiently excited by ultraviolet light reflected by thereflective film 73. For example, in the above fluorescent material usingtrivalent Eu contained in the first fluorescent material layer 81 as theluminescence center, the light is converted into light having a narrowwavelength distribution in the vicinity of 620 nm. Thus, red visiblelight can be efficiently obtained.

Furthermore, the blue, green and yellow visible lights can beefficiently achieved by exciting the blue, green and yellow fluorescentmaterials included in the second fluorescent material layer 82.Furthermore, as mixed colors of them, it is possible to achieve whitelight or light of various colors with high efficiency and with goodcolor rendering properties.

According to the semiconductor light emitting apparatus 500, lighthaving a desired color can be achieved efficiently.

As described above, according to the semiconductor light emitting deviceaccording to the embodiments, the light extraction efficiency can beimproved while enhancing the heat dissipation property.

Hereinabove, exemplary embodiments or their modifications are described.However, the invention is not limited to these examples. For example,examples made by a person skilled in the art by suitably adding ordeleting constituents or adding design modification with respect to theabove-mentioned embodiments or their modifications, or examples made bysuitably combining features of the embodiments, are also included withinthe scope of the invention to the extent that the purport of theinvention is included.

While certain embodiments have been described, these embodiments havebeen presented by way of example only, and are not intended to limit thescope of the inventions. Indeed, the novel embodiments described hereinmay be embodied in a variety of other forms; furthermore, variousomissions, substitutions and changes in the form of the embodimentsdescribed herein may be made without departing from the spirit of theinventions. The accompanying claims and their equivalents are intendedto cover such forms or modifications as would fall within the scope andspirit of the invention.

1-20. (canceled)
 21. A semiconductor light emitting device comprising: afirst semiconductor layer of a first conductivity type, the firstsemiconductor layer including a first portion and a second portion; asecond electrode provided apart from the first semiconductor layer alonga first direction intersecting a second direction from the first portiontoward the second portion, the second electrode including: a first partprovided apart from the second portion along the first direction, asecond part provided apart from the first portion along the firstdirection, and a third part; a second semiconductor layer of a secondconductivity type provided between the first part and the secondportion, the second semiconductor layer contacting the first part; alight emitting layer provided between the second semiconductor layer andthe second portion; a first electrode including a contact part and alead part, the contact part being provided between the first portion andthe second part, the contact part contacting the first portion, the leadpart being electrically continuous with the contact part; a dielectricmember; and a substrate being electrically continuous with the secondelectrode, the first part being disposed between the substrate and thesecond semiconductor layer, the second part being disposed between thesubstrate and the contact part, a stacking body including the firstsemiconductor layer, the second semiconductor layer, and the lightemitting layer, the substrate having an edge portion not overlapping thestacking body in the first direction, the third part being disposedbetween the edge portion and the lead part, and the dielectric memberbeing disposed between the contact part and second part, and between thelead part and the third part.
 22. The device according to claim 21,wherein the first part includes silver, and the second part includestitanium.
 23. The device according to claim 22, wherein a part of thesecond part is disposed between the first part and the dielectricmember.
 24. The device according to claim 21, wherein the dielectricpart is not provided between first part and the substrate.
 25. Thedevice according to claim 21, wherein the lead part includes a padelectrode.
 26. The device according to claim 21, further includes a padelectrode electrically continuous with the first electrode, the padelectrode overlapping the edge portion in the first direction.
 27. Thedevice according to claim 21, wherein the second electrode includes aplated metal.
 28. The device according to claim 21, wherein the firstelectrode includes aluminum.
 29. The device according to claim 21,wherein the first semiconductor layer includes a first nitridesemiconductor, the second semiconductor layer includes a second nitridesemiconductor, and the light emitting layer includes a third nitridesemiconductor.
 30. The device according to claim 21, wherein thestacking body has a first face on a side of the first semiconductorlayer, and a second face on a side of the second semiconductor layer, anamount of a light emitted from the light emitting layer and exiting fromthe first face is more than an amount of a light emitted from the lightemitting layer and exiting from the second face.
 31. The deviceaccording to claim 21, wherein the stacking body has a first face on aside of the first semiconductor layer, and a second face on a side ofthe second semiconductor layer, the second face has a concave partreaching the first semiconductor layer, and the contact part contactsthe first semiconductor layer at a bottom of the concave part.